The present invention is related to reproducing data from a disk, and more particularly to apparatus (and the corresponding method) operative to ascertain quickly and accurately the type of disk from which the data is reproduced by playback apparatus (or the playback steps).
It is apparent that the popularity of a Digital Video Disk (DVD) is currently growing very rapidly. Typically, the DVD may be a Single Layer disk (DVD SL disk) with one data layer for recording/reproducing data or a Dual Layer disk (DVD DL disk) having two data layers. Both disk types can be used interchangeably by a reproducing device (apparatus). In addition to the DVD, data from a Compact Disk (CD) can also be reproduced by this reproducing device. Thus, at least three disk types may be used by the single reproducing device.
Although the physical shape (diameter) of each disk type (DVD SL disk, DVD DL disk, and CD) may be the same, each of these disks operates with unique parameters (operating conditions) set by the reproducing device. This is due to the fact that data formats and/or internal disk structures for data storage are different among the DVD SL disk, DVD DL disk, and CD, for example. As a result, the reproducing device which can employ any one of the above-mentioned three disks must ascertain which disk type is currently in use.
A control data area is provided in the DVD where the data relating to the disk type may be recorded. Similarly, in the CD, a TOC (Table of Contents) area is allocated for recording, among other things, the data relating to the disk type. Hence, it appears that it is possible to easily determine the type of disk loaded in the device by simply accessing the control data area or the TOC area and by retrieving (reading) the appropriate information in those areas.
A problem, however, is encountered when the reproducing device is operative to read data on the disk. Namely, in order to read data correctly, it is necessary to initialize various servos (drivers) in the reproducing device (such as a focus servo, a tracking servo, a spindle servo, and the like) to their proper states (settings). Unless these servos are locked (the proper operating conditions are established), the data cannot be read from the control data area or the TOC area. For example, it is necessary to adjust the power of a laser beam or the gain of the reproduced RF signal amplification in the reproducing device prior to reproducing data from the disk. If these parameters are not set correctly, the data cannot be read. The disk type, therefore, cannot be determined by using the above seemingly simple approach.
Accordingly, it would be preferable to determine the disk type prior to setting the necessary parameters in the reproducing device. In this respect, it is possible to employ a trial-and-error method. However, after inserting the disk in the device, it would take a long time for the reproducing device to reach a state where the reproduction of data is performed. The situation, of course, becomes even worse as the number of possible disk types increases.
A need therefore exists for a device and method that overcomes the above disadvantage.